Hermetically encapsulated refrigerant compressor

ABSTRACT

The hermetically encapsulated refrigerant compressor includes a cylinder, a reciprocating piston arranged in the cylinder and having a reciprocating piston axis, a valve plate comprising a suction valve opening and a discharge valve, a cylinder head on the side of the valve plate facing away from the cylinder, a cylinder head cover which has an outlet for compressed refrigerant, and a sound absorber. On the side of the valve plate facing away from the cylinder, a nozzle is arranged as an inlet for refrigerant to be drawn in, the nozzle having a first end arranged at the suction valve opening and a second end. The nozzle is inclined at a maximum angle of inclination of between −45° and +45° in relation to the reciprocating piston axis. The sound absorber has a housing with a suction opening into which the second end of the nozzle leads.

The present invention relates to hermetically encapsulated refrigerant compressors of the reciprocating compressor type, and in particular to such compressors for refrigerating machines used in household appliances such as refrigerators, freezers and small air conditioners.

Conventional hermetically encapsulated refrigerant compressors comprise a cylinder formed in a cylinder block and having an open end, a reciprocating piston arranged in the cylinder, a valve plate with a suction valve and a discharge valve, with the valve plate being attached to the cylinder block at the open end of the cylinder, a cylinder head located above the valve plate and defining a cylinder head space around the side of the valve plate facing away from the cylinder, the cylinder head having a cylinder head cover comprising an inlet for refrigerant to be drawn in and an outlet for compressed refrigerant.

Sound absorbers designed for drawing in refrigerant are an important component of the refrigerant compressor. Their tasks are to guide the refrigerant, to dampen noise caused by the refrigerant being drawn in periodically and to thermally insulate the refrigerant sucked into the cylinder against the environment. In doing so, the size of the sound absorber, in particular its length, shape and internal volume, has a very strong effect on the performance of the compressor. Due to the current trend of keeping the dimensions of these compressors, in particular their height, as small as possible, the size of the sound absorbers is also forcibly restricted, which can have a negative impact on the performance of the compressor.

In general, refrigerant compressors have a reciprocating piston axis perpendicular to the valve plate, whereby the inlet opening for the refrigerant in the valve plate is located transversely to the axis of the reciprocating piston. Refrigerant compressors are usually installed in devices in such a way that the axis of the reciprocating piston is arranged essentially horizontally. In order to connect the sound absorber to the inlet opening of the valve plate, conventional sound absorbers have a duct for discharging the refrigerant that has been drawn in, the duct having a deflection so that two duct sections being at an angle to one another are formed. This deflection is necessary so that, on the one hand, the duct can be connected to the inlet opening of the valve plate and, on the other hand, the sound absorber can be arranged opposite to the inlet opening at a distance and in an angularly offset manner in order to optimally utilize the available installation space. Accordingly, the duct section of the sound absorber that abuts the inlet opening of the valve plate is aligned at right angles to the valve plate. Since the sound absorber generally cannot be arranged on a level with the cylinder head cover due to lack of space, the above-mentioned deflection and the second duct section, which extends from the sound absorber and runs perpendicularly to the reciprocating piston axis, are provided. With this configuration, the sound absorber can be arranged at a place below the cylinder block. A reciprocating compressor with a sound absorber designed in this way is disclosed, for example, in patent application US 2009/0038329 A1, in particular in FIG. 4. Refrigerant is drawn in from the sound absorber through the duct and conducted to the suction valve of the valve plate. However, due to the shape and size, in particular the length and the deflection of the duct, a few disadvantages are created, which will be explained in further detail below.

A significant disadvantage is caused by the deflection of the duct. Due to this deflection, the refrigerant is directed to the outer edge of the duct by the centrifugal force and impinges only a small area of the inlet opening of the suction valve. As a result, it is more difficult for the refrigerant to pass through the inlet opening, which can lead to a backlog of refrigerant and, consequently, to performance losses of the compressor.

Another disadvantage is that, as a result of the deflection, a laminar flow of the refrigerant, which is preferred for an error-free operation of the refrigerant compressor, can become unstable, whereby turbulences form especially in the area of the deflection. Such turbulences are additionally promoted by the considerable length of the duct section running perpendicularly to the reciprocating piston axis so that, as a result, flow losses will arise, which will additionally limit the performance of the refrigerant compressor.

Another significant disadvantage is that, due to the ever smaller compressor housings required by device makers, the sound absorbers that draw in refrigerant inevitably also have to become smaller and smaller. So far, the reason for this has mainly been that the known sound absorbers are arranged below the cylinder head, which causes their duct section running perpendicularly to the reciprocating piston axis to be required as well. Because of the resulting reduction in the cavity contained in the sound absorber, intake noises cannot be dampened so well, which leads to a noisy operation of the refrigerant compressor.

From WO 2010/255534 A1, a refrigerant compressor is known which has a hermetically encapsulated housing, a cylinder formed in a cylinder block and having an open end, a reciprocating piston arranged in the cylinder, a valve plate having a suction valve opening with a suction valve and a discharge opening with a discharge valve, and a cylinder head on the side of the valve plate facing away from the cylinder, the cylinder head defining a cylinder head space above the valve plate, which space is divided by a wall formed in the cylinder head into a suction chamber and a discharge chamber above a portion of the valve plate which contains the discharge valve. For the thermal insulation of the gas drawn in in the cylinder head space, thermal insulation means are provided which either are designed as a lining of the interior of the cylinder head with a thermally insulating material, such as, e.g., a heat-insulating film, or consist of a separate insert in the form of a hollow body, which also serves for sound insulation and is arranged in the interior of the cylinder head with minimum contact points. The hollow body is arranged in the cylinder head space of the cylinder head, as a result of which its volume is inevitably small and sound absorption is therefore low. The thermal insulation is also relatively low in this refrigerant compressor.

By means of the present invention, a refrigerant compressor is to be provided which overcomes the above-mentioned disadvantages of the prior art and allows quiet operation even in case of a small size.

The present invention achieves the given objects by providing a hermetically encapsulated refrigerant compressor of the reciprocating compressor type having the features of claim 1. Advantageous embodiments of the invention become apparent from the dependent claims, the specification and the drawings.

The present invention provides a hermetically encapsulated refrigerant compressor comprising a cylinder formed in a cylinder block and having an open end, a reciprocating piston arranged in the cylinder and having a reciprocating piston axis along which the reciprocating piston reciprocates, a valve plate comprising a suction valve opening and a discharge valve, the valve plate being attached to the cylinder block at the open end of the cylinder, a cylinder head on the side of the valve plate facing away from the cylinder, the cylinder head defining a cylinder head space at least above a portion of the valve plate which contains the discharge valve, the cylinder head comprising a cylinder head cover which has an outlet for compressed refrigerant, and a sound absorber. On the side of the valve plate facing away from the cylinder, a nozzle is arranged as an inlet for refrigerant to be drawn in, the nozzle having a first end arranged at the suction valve opening and a second end opposite to the first end. The nozzle is inclined at a maximum angle of inclination of between −45° and +45° in relation to the reciprocating piston axis. The sound absorber is arranged outside of the cylinder head and has a housing that defines a cavity. A suction opening for refrigerant to be drawn into the cavity and a discharge opening for refrigerant to be discharged from the cavity are formed in the housing. The nozzle passes through the cylinder head cover or is arranged outside of the cylinder head space, with the second end of the nozzle leading to the cavity of the sound absorber through the discharge opening.

As a result, a short suction path can be implemented, which, in comparison to the prior art, is designed without a right-angled deflection, whereby the occurrence of turbulences and flow losses is significantly reduced or even completely prevented. Furthermore, the short suction path has the advantage that, on the one hand, material for the production of the sound absorber can be saved and, on the other hand, complex forming processes, which are necessary for creating the deflections of the ducts of conventional sound absorbers, can be omitted. In addition, the refrigerant compressor can be manufactured more easily and quickly due to the simplified design, whereby production costs are reduced.

Moreover, it is advantageous that due to the fact that the duct having a deflection has been omitted, the refrigerant flows evenly through the entire cross-section of the nozzle and is thus conducted into the entire area of the suction valve opening. A backlog of refrigerant can thus be avoided, which means that refrigerant can be drawn into the cylinder more efficiently.

A particular advantage of the invention is that the sound absorber can be arranged on a level with the cylinder head cover, as a result of which the cavity in the sound absorber can be dimensioned on a comparatively large scale even if the compressors are small. Intake noises can thus be dampened better so that a quiet operation of the refrigerant compressor can be achieved.

According to a preferred embodiment of the invention, the nozzle is designed as a pipe section or a conical hollow body. The nozzle can have a curved or kinked design, with the maximum angle of inclination of any portion of the nozzle ranging between −45° and +45° in relation to the reciprocating piston axis. Due to the inclination of the nozzle or portions of the nozzle which is comparatively low or non-existent in comparison to the prior art, the suction path is short and turbulences and flow losses in the nozzle remain low, whereby it is ensured that sufficient refrigerant is drawn in at any time.

In a preferred embodiment of the refrigerant compressor according to the invention, the nozzle is designed in one piece with the cylinder head cover. This embodiment provides advantages due to a simple manufacturing process of the cylinder head cover with the nozzle, e.g., by a die-casting or injection process, and minimizes temperature stresses in the cylinder head cover.

The cylinder head cover and the nozzle are preferably made of a metal or a metal alloy, in particular aluminium or an aluminium alloy, or of a synthetic material, which optionally is fibre-reinforced.

In an embodiment of the refrigerant compressor according to the invention, the housing of the sound absorber is made of a synthetic material. This embodiment exhibits a particularly good thermal insulation of the refrigerant against the environment.

According to a further embodiment of the invention, the nozzle has a shape which essentially corresponds to the cross-sectional area of the suction valve opening, in particular, however, an essentially circular or elliptical shape. As a result, the advantage is obtained that refrigerant that has been drawn in can enter the suction valve opening without hindrance and without any performance-limiting suction losses.

A particularly good sound absorption effect and very low turbulences of the refrigerant as it is being drawn in by the reciprocating piston result if the discharge opening is arranged in a side wall of the housing of the sound absorber. In this connection, it has been shown that such effects can be increased even further by the discharge opening being arranged in the upper half, preferably in the upper third, of a side wall of the housing of the sound absorber.

In an alternative embodiment of the refrigerant compressor, the discharge opening is arranged in a top side or a bottom side of the housing of the sound absorber. However, due to the small inclination of the nozzle of not more than ±45° in relation to the reciprocating piston axis, the wall of the top side or, respectively, the bottom side of the housing must be inclined accordingly in this embodiment so that the nozzle can lead to the discharge opening of the housing.

The invention will now be explained in further detail on the basis of exemplary embodiments, with reference to the drawings.

FIG. 1 is a sectional view of a hermetically encapsulated refrigerant compressor with a cylinder head cover comprising a nozzle according to the present invention.

FIG. 2 shows a perspective view of the refrigerant compressor depicted in FIG. 1 .

FIG. 3 shows a perspective view of the cylinder head cover integral with the nozzle.

Hereinafter, reference is made to FIGS. 1 and 2 , which show a hermetically encapsulated refrigerant compressor 1 according to the invention. The refrigerant compressor 1 comprises a cylinder 3 formed in a cylinder block 2 and having an open end, a reciprocating piston 4 arranged in the cylinder 3, a valve plate 5 comprising a suction valve opening 6 and a discharge valve 7, the valve plate being attached to the cylinder block 2 at the open end of the cylinder 3, and a cylinder head 8 located above the valve plate 5 and defining a cylinder head space 9 around the side of the valve plate 5 facing away from the cylinder 3. The reciprocating piston 4 has a reciprocating piston axis 4 a along which the reciprocating piston 4 reciprocates. The cylinder head 8 has a cylinder head cover 10 which has an inlet for refrigerant to be drawn in and an outlet for compressed refrigerant. A sound absorber 12 is connected to the inlet of the cylinder head cover in that the inlet for refrigerant to be drawn in is formed in the cylinder head cover 10 as a nozzle 11 passing through the cylinder head cover 10, with a first end 11 a of the nozzle 11 being arranged at the suction valve opening 6 and a second end 11 b of the nozzle 11 protruding from the cylinder head cover 10. However, the cylinder head 8 could also be configured such that it covers only a portion of the valve plate 5, said portion containing the discharge valve 7. It is also not necessary for the nozzle 11 to pass through the cylinder head cover 10, but it could also be arranged outside of the cylinder head space 9, i.e., to the side, above or below the cylinder head cover 10. The nozzle 11 can be designed in one piece with the cylinder head cover 10. As an alternative, the nozzle 11 and the cylinder head cover 10 can be designed as separate components. It is also possible to design the nozzle 11 in several parts, with a one-piece design being preferred. In the present case, the nozzle 11 is designed as a straight pipe section and has a longitudinal axis 11 c which can be arranged at an angle of inclination a of between −45° and +45° in relation to the reciprocating piston axis 4 a, wherein the angle of inclination a between the longitudinal axis 11 c of the nozzle 11 and the reciprocating piston axis 4 a is 0° in the illustrated exemplary embodiment, i.e., the nozzle 11 is arranged in parallel to the reciprocating piston axis 4 a. Depending on the position of the suction valve opening 6 in the valve plate 5, a coaxial arrangement of the nozzle 11 in relation to the reciprocating piston axis 4 a is also provided in alternative embodiments of the invention. The nozzle 11 could also be designed as a conical hollow body and/or could have a curved or kinked design, with the maximum angle of inclination a of each portion of the nozzle 11 in relation to the reciprocating piston axis 4 a also being between −45° and +45° in such an embodiment.

The sound absorber 12 has a housing 12 a defining a cavity 12 d. In the housing 12 a of the sound absorber 12, a suction opening 12 b for refrigerant to be drawn into the cavity 12 d and a discharge opening 12 c for refrigerant to be discharged from the cavity 12 d are formed. In this exemplary embodiment of the refrigerant compressor 1, the discharge opening 12 c is arranged in a side wall of the housing 12 a of the sound absorber 12. In the installation position of the sound absorber 12, the discharge opening 12 c is in this case located in the upper half, more precisely in this exemplary embodiment in the upper third of a side wall of the housing 12 a of the sound absorber 12. The second end 11 b of the nozzle 11 leads through the discharge opening 12 c into the cavity 12 d of the sound absorber 12, wherein, in the illustrated embodiment, the second end 11 b of the nozzle 11 protrudes through the discharge opening 12 c of the sound absorber 12 into the cavity 12 d of the sound absorber. The first end 11 a of the nozzle 11 rests directly on the suction valve opening 6 of the valve plate 5.

The nozzle 11 preferably has a shape adapted to the cross-sectional area of the suction valve opening 6, e.g., a substantially circular or elliptical shape or combinations thereof. For example, the nozzle 11 can be shaped like a mouth, as can be seen in FIG. 3 , wherein the ends 11 a, 11 b of the nozzle 11 can each be shaped differently from one another. For example, the first end 11 a of the nozzle 11 can have a mouth-shaped design, and the second end 11 b can have a circular design.

The cylinder head cover 10 and the nozzle 11 are preferably designed as an integral unit, which can be produced by injection moulding, for example. If the nozzle 11 and the cylinder head cover 10 are designed separately, the cylinder head cover 10 can be connected to the nozzle 11 by means of a non-positive connection, e.g., a press fit, or by screw threads or gluing. The material of the nozzle 11 is preferably a metal or a metal alloy, e.g., aluminium or an aluminium alloy, but can also be another material known from the prior art, such as, e.g., a synthetic material, which optionally is fibre-reinforced. The cylinder head cover 10 is preferably made of the same material as the nozzle 11.

In the illustrated embodiment, the sound absorber 12 is arranged at the second end 11 b of the nozzle 11 which is opposite to the valve plate 5, wherein the nozzle 11 can be several centimetres, e.g. up to 10 cm, long and can protrude from the cylinder head cover 10 for a length of several centimetres, e.g. up to 5 cm. The second end 11 b of the nozzle 11 which faces away from the valve plate 5 is thereby arranged at the discharge opening 12 c of the sound absorber 12 and has a shape of its external surface which is adapted to the contour of the discharge opening 12 c, whereby the second end 11 b of the nozzle 11 can be inserted through the discharge opening 12 c of the housing 12 a of the sound absorber 12 into the cavity 12 d of the housing 12 a of the sound absorber 12 in an essentially sealing manner. The sound absorber 12 is preferably connected to the nozzle 11 by means of a non-positive connection, in particular by means of a press fit, in such a way that a tight connection is created. In the simplest case, this connection can be established by attaching the sound absorber 12 to the nozzle 11. Alternatively, the sound absorber 12 can also be integrally bonded to the nozzle 11, e.g., by gluing or welding, in which case the sound absorber 12 and the nozzle 11 are preferably made of the same material. However, for reasons of sound pressure dampening and thermal insulation of the refrigerant, the material of the sound absorber 12 is preferably a synthetic material. In FIGS. 1 and 2 , the sound absorber 12 is shown schematically as having a simple cuboid shape. However, the sound absorber 12 can, of course, also have other shapes, which, on the one hand, result from the shape of the other parts of the refrigerant compressor 1 and, on the other hand, are configured in such a way that the sound absorber 12 has a volume of its cavity 12 d that is as large as possible.

FIG. 3 shows a perspective view of the cylinder head cover 10 comprising the nozzle 11. The cylinder head cover 10 having a circular design is connected to the cylinder head 8, which also has a circular design, by means of a non-positive connection, in particular a screw connection, whereas, alternatively, they can also be materially interconnected, e.g., by means of a weld joint. Both the cylinder head cover 10 and the cylinder head 8 can have a shape which deviates from the circular cross-sectional shape, with the cylinder head cover 10 and the cylinder head 8 preferably having the same cross-sectional shape. In addition, a seal not shown in the figures, e.g., an O-ring, can be arranged on the surface 10 a of the cylinder head cover 10 which faces the valve plate 5 in order to tightly connect the cylinder head cover 10 to the cylinder head 8. 

1.-8. (canceled)
 9. A hermetically encapsulated refrigerant compressor comprising a cylinder formed in a cylinder block and having an open end, a reciprocating piston arranged in the cylinder and having a reciprocating piston axis along which the reciprocating piston reciprocates, a valve plate comprising a suction valve opening and a discharge valve, the valve plate being attached to the cylinder block at the open end of the cylinder, a cylinder head on the side of the valve plate facing away from the cylinder, the cylinder head defining a cylinder head space at least above a portion of the valve plate which contains the discharge valve, the cylinder head comprising a cylinder head cover which has an outlet for compressed refrigerant, wherein, on the side of the valve plate facing away from the cylinder, a nozzle is arranged as an inlet for refrigerant to be drawn in, the nozzle having a first end leading to the suction valve opening and a second end opposite to the first end, with the nozzle being inclined at a maximum angle of inclination of between −45° and +45° in relation to the reciprocating piston axis, and wherein the refrigerant compressor has a sound absorber arranged outside of the cylinder head and comprising a housing, the housing defining a cavity and a suction opening for refrigerant to be drawn into the cavity and a discharge opening for refrigerant to be discharged from the cavity being formed in the housing, the nozzle passing through the cylinder head cover or, if the cylinder head covers only a portion of the valve plate which contains the discharge valve, the nozzle being arranged outside of the cylinder head space, the second end of the nozzle leading to the cavity of the sound absorber through the discharge opening.
 10. A refrigerant compressor according to claim 9, wherein the nozzle comprises a pipe section or a conical hollow body.
 11. A refrigerant compressor according to claim 9, wherein the nozzle has a curved or kinked configuration, with the maximum angle of inclination of any portion of the nozzle ranging between −45° and +45° in relation to the reciprocating piston axis.
 12. A refrigerant compressor according to claim 9, wherein the nozzle is integral with the cylinder head cover.
 13. A refrigerant compressor according to claim 9, wherein the nozzle has a shape which essentially corresponds to the cross-sectional area of the suction valve opening, in particular an essentially circular or elliptical shape.
 14. A refrigerant compressor according to claim 9, wherein the housing of the sound absorber is made of a synthetic material.
 15. A refrigerant compressor according to claim 9, wherein the discharge opening is arranged in a side wall of the housing of the sound absorber, with the discharge opening being arranged in the upper half of a side wall of the housing of the sound absorber.
 16. A refrigerant compressor according to claim 9, wherein the discharge opening is arranged in a top side or a bottom side of the housing of the sound absorber. 